Granulating Chronic Wound Dressing

ABSTRACT

In some non-limiting examples, a system for stimulating tissue growth at a tissue site may include an interactive body including a body mass and a tissue contact surface configured to contact the tissue site. A plurality of struts and a plurality of voids may be exposed at the tissue contact surface, and may define a tissue interface pattern at the tissue contact surface. The tissue interface pattern may be configured to engage the tissue site and to create tissue deformation in combination with the body mass. Also provided are other systems, apparatus, and methods suitable for stimulating tissue growth.

RELATED APPLICATIONS

The present application claims the benefit, under 35 USC § 119(e), of the filing of U.S. Provisional Patent Application Ser. No. 62/517,425, entitled “Granulating Chronic Wound Dressing,” filed Jun. 9, 2017. The provisional application is incorporated herein by reference for all purposes.

TECHNICAL FIELD

This application relates generally to medical treatment systems and, more particularly, but not by way of limitation, to apparatus, dressings, systems, and methods that may be suitable for treating a tissue site.

BACKGROUND

Clinical studies and practice have shown that providing a reduced pressure in proximity to a tissue site may augment and accelerate growth of new tissue at the tissue site. The applications of this phenomenon are numerous and may, without limitation, involve wound healing. This treatment may be referred to as “negative pressure wound therapy,” “reduced pressure therapy,” or “vacuum therapy.” Reduced pressure therapy may provide a number of benefits, including migration of epithelial and subcutaneous tissues, improved blood flow, micro-deformation of tissue, and macro-deformation of tissue. These benefits may result in increased development of granulation tissue and faster healing times. Conventional reduced pressure therapy may employ a reduced pressure source and associated system and control components to communicate the reduced pressure to tissue at the tissue site through a manifold or porous device.

Some tissue sites or wounds may not be a candidate for conventional reduced pressure therapy, but may benefit from the increased development of granulation tissue and faster healing times offered by this treatment. Accordingly, improvements to apparatus, dressings, systems, and methods for stimulating tissue growth without the application of reduced pressure and the associated system and control components may be desirable.

SUMMARY

In some illustrative, non-limiting examples, a system for stimulating tissue growth at a tissue site may include an interactive body that may be configured to create tissue deformation at the tissue site. The interactive body may include a tissue contact surface, a plurality of struts, a plurality of voids, a tissue interface pattern, and a body mass. The tissue contact surface may be configured to contact the tissue site. The plurality of struts and the plurality of voids may be exposed at the tissue contact surface. The tissue interface pattern may be defined by the plurality of struts and the plurality of voids at the tissue contact surface. The tissue interface pattern may be configured to engage the tissue site, and the body mass may be configured to create the tissue deformation in combination with the tissue interface pattern.

In some illustrative, non-limiting examples, a system for stimulating tissue growth at a tissue site may include a porous foam. The porous foam may include a tissue contact surface and a plurality of struts positioned or exposed at the tissue contact surface. The plurality of struts may be configured to contact the tissue site and to create tissue deformation at the tissue site. In some examples, the porous foam may have a porosity between about 20 pores per inch to about 35 pores per inch. Further, the porous foam may be configured to provide a contact force at least between the plurality of struts and the tissue site to create the tissue deformation without the application of a reduced pressure.

In some illustrative, non-limiting examples, the system may include a plurality of voids. The plurality of voids and the plurality of struts may be exposed at the tissue contact surface and configured to engage the tissue site. Further, in some non-limiting examples, the porous foam may include a hydrophobic reticulated polyurethane foam. In some non-limiting examples, an absorbent member may be positioned proximate to the porous foam such that the porous foam is configured to be positioned between the absorbent member and the tissue site. The absorbent member may be configured to absorb a fluid communicated from the tissue site through the porous foam, and to swell and to exert an auxiliary force on the tissue site through the porous foam when the fluid is absorbed. In some non-limiting examples, the system may include a sealing member configured to provide a sealed space between the sealing member and the tissue site. The porous foam and the absorbent member may be configured to be positioned in the sealed space.

In some illustrative, non-limiting examples a method for stimulating tissue growth at a tissue site may include providing an interactive body comprising a tissue contact surface. The tissue contact surface may include a plurality of struts and a plurality of voids exposed at the tissue contact surface. Further, the method may include positioning the tissue contact surface in contact with the tissue site, and engaging the plurality of struts and the plurality of voids with a tissue at the tissue site to create a contact force on the tissue. Further, the method may include deforming the tissue at the tissue site by operation of the contact force without an application of reduced pressure.

Other aspects, features, and advantages of the illustrative examples will become apparent with reference to the drawings and detailed description that follow.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of an illustrative example of a system for stimulating tissue growth depicting an illustrative example of an interactive body positioned at a tissue site;

FIG. 2 is a detail view of an illustrative example of a tissue contact surface of the interactive body of FIG. 1 in contact with the tissue site, taken at reference FIG. 2 shown in FIG. 1;

FIG. 3A is a cross-sectional, detail view of another illustrative example of an interactive body;

FIG. 3B is a cross-sectional, detail view of another illustrative example of an interactive body;

FIG. 3C is a cross-sectional, detail view of another illustrative example of an interactive body;

FIG. 4A is a plot of Mean Percent Change in Wound Volume from days 0-6 for Test Articles 1-8 and Control Articles 1-2;

FIG. 4B is a bar graph of Mean Granulation Tissue Thickness, measured in microns, for Test Articles 1-8 and Control Articles 1-2 produced over a 6 day testing period;

FIG. 4C is a bar graph of Overall Inflammation, scored from 1-5, for Test Articles 1-8 and Control Articles 1-2 produced over a 6 day testing period; and

FIG. 4D is a bar graph of Edema, scored from 1-5, for Test Articles 1-8 and Control Articles 1-2 produced over a 6 day testing period.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

In the following detailed description of illustrative example embodiments, reference is made to the accompanying drawings that form a part of this disclosure. Other embodiments may be used, and logical, structural, mechanical, electrical, and chemical changes may be made without departing from the scope of this disclosure. Further, the description may omit certain information known to those skilled in the art. The description is also non-limiting, and the appended claims define the scope of the illustrative embodiments.

Referring to FIG. 1, in some illustrative, non-limiting examples, a system 110 for stimulating tissue growth at a tissue site 112 may include an interactive body 114 that may be configured to create tissue deformation at the tissue site 112. The interactive body 114 may be configured to create the tissue deformation by a contact force 115 between the interactive body 114 and the tissue site 112 without the application of an external force, such as, without limitation, a force that may be generated by a machine or a chemical. For example, the interactive body 114 may be configured to create the tissue deformation without the application of a reduced pressure from a reduced pressure source, which may allow some tissue sites that are not candidates for reduced pressure therapy to experience an increase in granulation tissue development and healing that conventional wound dressings designed for use without reduced pressure cannot provide. The interactive body 114 may be used with a dressing, incorporated as a component within a dressing, or entirely form a dressing. Accordingly, the interactive body 114 may be used independently or in combination with one or more components of the system 110 as described herein, and thus, components of the system 110 may be omitted as desired to suit a particular tissue site or therapeutic application. The interactive body 114 may be used alone or independently of other component of the system 110 if desired.

As used herein, the term “tissue site” may refer to a wound or defect located on or within any tissue, including but not limited to, bone tissue, adipose tissue, muscle tissue, neural tissue, dermal tissue, vascular tissue, connective tissue, cartilage, tendons, or ligaments. The term “tissue site” may further refer to areas of any tissue that are not necessarily wounded or defective, but are instead areas in which it is desired to add or promote the growth of additional tissue. Further, as used throughout this disclosure, “or” does not require mutual exclusivity.

The tissue site 112 may extend through or otherwise involve an epidermis 116, a dermis 118, and a subcutaneous tissue 120. The tissue site 112 may be a sub-surface tissue site as depicted in FIG. 1 that extends below the surface of the epidermis 116. Further, the tissue site 112 may be a surface tissue site (not shown) that predominantly resides on the surface of the epidermis 116. The system 110 may also be utilized without limitation at other tissue sites. Further, the tissue site 112 may have an edge 122 or perimeter defining an outer boundary of the tissue site 112. Other tissue, such as the epidermis 116, may reside beyond the edge 122 of the tissue site 112, and may surround the tissue site 112.

In some embodiments, the system 110 may include a sealing member 128. The sealing member 128 may be configured to provide a sealed space 130 between the sealing member 128 and the tissue site 112. The interactive body 114 may be configured to be positioned in the sealed space 130.

The sealing member 128 may be formed from any material that allows for a fluid seal. A fluid seal may be a seal adequate to protect the tissue site 112 from contaminants. The sealing member may comprise, for example, one or more of the following materials: hydrophilic polyurethane; cellulosics; hydrophilic polyamides; polyvinyl alcohol; polyvinyl pyrrolidone; hydrophilic acrylics; hydrophilic silicone elastomers; an INSPIRE 2301 material from Expopack Advanced Coatings of Wrexham, United Kingdom having, for example, an MVTR (inverted cup technique) of 14400 g/m²/24 hours and a thickness of about 30 microns; a thin, uncoated polymer drape; natural rubbers; polyisoprene; styrene butadiene rubber; chloroprene rubber; polybutadiene; nitrile rubber; butyl rubber; ethylene propylene rubber; ethylene propylene diene monomer; chlorosulfonated polyethylene; polysulfide rubber; polyurethane (PU); EVA film; co-polyester; silicones; a silicone drape; a 3M TEGADERM® drape; a polyurethane (PU) drape, such as one available from Avery Dennison Corporation of Pasadena, Calif.; polyether block polyamide copolymer (PEBAX), for example, from Arkema, France; Expopack 2327; or other appropriate material.

The sealing member 128 may be vapor permeable and liquid impermeable, thereby allowing vapor and inhibiting liquids from exiting the sealed space 130. In some embodiments, the sealing member 128 may be a flexible, breathable film, membrane, coating, or sheet having a high MVTR of, for example, at least about 300 g/m² per 24 hours. In other embodiments, a low or no vapor transfer drape may be used. The sealing member 128 may comprise a range of medically suitable films having a thickness between about 15 microns (μm) to about 50 microns (μm). In some embodiments, the sealing member 128 may be a coating or layer adhered to or forming part of an exterior-facing surface of the interactive body 114 that is configured to face away or outward from the tissue site 112.

In some embodiments, the sealing member 128 may be deployed with an adhesive 132 or bonding agent to secure and seal the sealing member 128 to tissue at or around the tissue site 112, such as the epidermis 116. For example, the adhesive 132 or bonding agent may be positioned between the sealing member 128 and tissue or the epidermis 116 around the tissue site. The adhesive 132 or bonding agent may be any medically acceptable adhesive or agent, such as an acrylic adhesive. In some embodiments, the adhesive 132 or bonding agent may form at least part of a surface of the sealing member 128, such as a coating, configured to face the tissue site 112 or tissue around the tissue site 112. In some embodiments, the adhesive 132 or bonding agent may be a separate component or layer of material, such as, for example, a hydrogel that may be positioned between the sealing member 128 and the tissue site 112 or tissue around the tissue site 112.

In some embodiments, the system 110 may include an absorbent member 138. The absorbent member 138 may be positioned proximate to the interactive body 114 in the sealed space 130 such that the interactive body 114 is positioned between the absorbent member 138 and the tissue site 112. The absorbent member 138 may be configured to absorb fluid communicated from the tissue site 112, and to swell upon absorption of the fluid. The fluid may be communicated from the tissue site 112 through the interactive body 114 to the absorbent member 138, for example, by a wicking action, by an absorbent gradient, by exposure to fluid in or around the interactive body 114, or other phenomena. The absorbent member 138 may be configured to exert an auxiliary force 139 on the tissue site 112, for example and without limitation, by operation of the swelling and expansion of the absorbent member 138 upon absorption of fluid, the fluid mass created by the absorption, or gravitational forces. The auxiliary 139 force may be exerted on the tissue site 112 through the interactive body 114, and may be directed toward, into, or along a surface or bed 140 of the tissue site 112. The auxiliary force 139 may also be enhanced by the positioning of the absorbent member 138 such that the absorbent member 138 is captured or held at the tissue site 112 by the sealing member 128 and placed between the sealing member and the interactive body 114.

The absorbent member 138 may be a hydrophilic material adapted to absorb fluid. In some embodiments, materials suitable for the absorbent member 138 may include, without limitation, super absorbent polymers and similar absorbent materials; LUQUAFLEECE® material; TEXSUS FP2326; BASF 402C; Technical Absorbents 2317, available from Technical Absorbents, Ltd. of Lincolnshire, United Kingdom; sodium polyacrylate super absorbers; cellulosics (carboxy methyl cellulose and salts such as sodium CMC); or alginates.

The interactive body 114 may have a thickness 144 as shown in FIG. 1. Referring to FIG. 2, in some embodiments, the interactive body 114 may include a tissue contact surface 146, a plurality of struts 148, a plurality of voids 150, a tissue interface pattern 152, and a body mass 154. The plurality of voids 150 may be cells, openings, or spaces distributed among the plurality of struts 148. The tissue interface pattern 152 may be defined on the tissue contact surface 146 by a measurement, ratio, fraction, or comparison of an amount of the struts 148 to the voids 150 positioned on the tissue contact surface 146. The body mass 154 may be defined by the size and material properties of the interactive body 114. In some embodiments, the interactive body 114 may include or be formed of a porous substrate material, having a suitable porosity as described herein, that may be fluid permeable. Further, in some embodiments, the interactive body 114 may include or be formed of a hydrophobic material. The hydrophobic material may prevent the interactive body 114 from directly absorbing fluid, such as exudate, from the tissue site 112, but allow the fluid to pass through.

The interactive body 114 may also act as a manifold. The term manifold may refer to a substance or structure configured for delivering fluids to or removing fluids from a tissue site through a plurality of voids, pores, pathways, or flow channels. The plurality of voids, pores, pathways, or flow channels may be interconnected to improve the distribution of fluid provided to and removed from an area around the manifold. Examples of manifolds may include, without limitation, devices that have structural elements arranged to form flow channels, cellular foam, such as closed-cell or open-cell foam, porous tissue collections, sintered polymers, and liquids, gels, and foams that include or cure to include flow channels.

The term porosity may refer to a measurement, ratio, fraction, or comparison of an amount of the struts 148 relative to the voids 150 in the interactive body 114. The plurality of struts 148 and the plurality of voids 150 may be defined by a porosity. Similarly, the tissue interface pattern 152 may be defined by a porosity of the interactive body 114 at the tissue contact surface 146. Porosity, also known as pore density, may be measured in Pores Per Inch (PPI), which designates the number of pores in one linear inch. Although porosity and pore density may be used to describe a porous material, such as foam, these principles may apply to other non-foam structures that include a void space.

In some embodiments, the interactive body 114 may include a porous foam or be formed of a foam. For example, in some embodiments, the foam may be a hydrophobic, reticulated, open-cell polyurethane or polyether foam that may be fluid permeable. Further, in some embodiments, ionic silver may be added to the foam by, for example, a micro bonding process. Other substances, such as anti-microbial agents, may be added to the foam as well.

In some embodiments, a non-reticulated foam or a foam comprised of biocompatible materials other than polyurethane may be used. In one embodiment, a bioabsorbable foam or other porous substrate may be employed. Examples of other materials that may be suitable porous foams or porous substrates include those formed from acrylics, acrylates, thermoplastic elastomers (for example, styrene ethylene butene styrene (SEBS) and other block copolymers), polyether block polyamide (PEBAX), silicone elastomers, poly caprolactam, poly lactic acid, and polyolefins, such as polythene and polypropylene. Still other biocompatible materials may be used if capable of being formed or otherwise made into a porous substrate as described herein.

The tissue contact surface 146 of the interactive body 114 may have a porosity that is less than about 39 pores per inch. For example, in some embodiments, the tissue contact surface 146 of the interactive body 114 may have a porosity between about 20 pores per inch to about 35 pores per inch. In embodiments of the interactive body 114 that use a foam, the foam may similarly have a porosity that is less than about 39 pores per inch or, for example, a porosity between about 20 pores per inch to about 35 pores per inch. In some embodiments, the foam may be positioned at the tissue contact surface 146 of the interactive body 114 or form the tissue contact surface 146 of the interactive body 114. The foam may carry the plurality of struts 148 and the plurality of voids 150.

The tissue contact surface 146 of the interactive body 114 may be configured to contact the tissue site 112. In some embodiments, the interactive body 114 may be sized to fit within the edge 122 or outer boundary of the tissue site 112 such that the interactive body 114 does not overlap or contact tissue around the tissue site, such as the epidermis 116. The plurality of struts 148 and the plurality of voids 150 may be exposed at the tissue contact surface 146. The plurality of struts 148 and the plurality of voids 150 may be configured to be positioned in direct physical contact with the tissue site 112. At least the plurality of struts 148 may be configured to engage the tissue site 112 and to create tissue deformation at the tissue site 112. As the tissue site 112 deforms, stretches, or moves in response to the plurality of struts 148, tissue at the tissue site 112 may deformed, stretched, or moved to fill at least a portion of a volume of the voids 150. Accordingly, the voids 150 may engage the tissue site 112, without limitation, by operation of tissue being deformed, stretched, or moved into the voids 150. The plurality of struts 148 and the plurality of voids 150 at the tissue contact surface 146 may collectively define the tissue interface pattern 152. The tissue interface pattern 152 may be configured to engage the tissue site 112 analogous to the plurality of struts 148 and the plurality of voids 150.

For example, the interactive body 114 may provide the contact force 115 at least between the plurality of struts 148 and the tissue site 112 to create the tissue deformation without the application of an external force, such as reduced pressure. The struts 148 and the voids 150 carried on the tissue contact surface 146 may be urged toward the bed 140 of the tissue site 112 under the contact force 115. The contact force 115 may be created in part by the body mass 154 of the interactive body 114, which may be enhanced by other components of the system 110, such as, for example, the previously described absorbent member 138. As the tissue contact surface 146 moves toward the bed 140, each of the struts 148 may create a stress substantially normal or orthogonal to the bed 140 of the tissue site 112, creating a distribution of deformation or strain across the bed 140 of the tissue site 112. As a result of this deformation or strain, tissue in the bed 140 may be deformed, stretched, or moved into the voids 150 as shown in FIG. 2.

For clarity, the contact force 115 is directed toward or into the bed 140 of the tissue site 112, and distributed across the bed 140, as shown in FIGS. 1 and 2. As described herein, the auxiliary force 139 may also be directed toward or into the bed 140 of the tissue site 112, and distributed across the bed 140 as shown in FIG. 1. However, the auxiliary force 139 is generated or associated with components of the system 110 other than the interactive body 114, and transmitted to the tissue site 112 through the interactive body 114. The auxiliary force 139 may enhance or increase the contact force 115.

As described herein, the tissue interface pattern 152 may be defined by the plurality of struts 148 and the plurality of voids 150 at the tissue contact surface 146. The tissue interface pattern 152 may be selectable according to the body mass 154, and the body mass 154 may be selectable according to the tissue interface pattern 152. For example, the tissue interface pattern 152 may be selected such that the plurality of struts 148 exposed at the tissue contact surface 146 have a shape or a surface area sized to create tissue deformation under the contact force 115 provided by the interactive body 114. The surface area of the plurality of struts 148 exposed at the tissue contact surface 146 may decrease as the size of the plurality of voids 150 increases. By way of example, a low porosity material having a porosity of 10 pores per inch will have a larger average void size or pore size compared to a high porosity material having a porosity of 60 pores per inch. Herein, a low porosity material may be a material that has a lower amount of pores per inch than a high porosity material having a higher amount of pores per inch. In a low porosity material, the larger size of the voids 150 or pores may occupy more space than the plurality of struts 148 in the tissue interface pattern 152, thereby reducing the surface area of the plurality of struts 148 exposed at the tissue contact surface 146 for engaging the tissue site 112. The plurality of struts 148 having a reduced surface area may require less of the contact force 115 to produce a desired amount of tissue deformation since the contact force 115 of this example will be exerted by a smaller surface area of the tissue interface pattern 152.

For example, FIGS. 3A-3C illustrate how variations in the porosity at the tissue contact surface 146 of the interactive body 114 can define the tissue interface pattern 152. In FIG. 3A, in some illustrative embodiments, the tissue contact surface 146 may be a tissue contact surface 146 a, and the tissue interface pattern 152 may be a tissue interface pattern 152 a. The tissue contact surface 146 a may have a porosity of 20 pores per inch, which may define the tissue interface pattern 152 a having the shape and surface area of the struts 148 and the voids 150 shown in FIG. 3A.

In FIG. 3B, in some illustrative embodiments, the tissue contact surface 146 may be a tissue contact surface 146 b, and the tissue interface pattern 152 may be a tissue interface pattern 152 b. The tissue contact surface 146 b may have a porosity of 30 pores per inch, which may define the tissue interface pattern 152 b having the shape and surface area of the struts 148 and the voids 150 shown in FIG. 3B. The struts 148 exposed at the tissue contact surface 146 b in the tissue interface pattern 152 b in FIG. 3B have a greater surface area than the struts 148 exposed at the tissue contact surface 146 a in the tissue interface pattern 152 a in FIG. 3A. Accordingly, the contact force 115 required for the tissue interface pattern 152 b may be greater than the tissue interface pattern 152 a to produce a desired amount of tissue deformation.

In FIG. 3C, in some illustrative embodiments, the tissue contact surface 146 may be a tissue contact surface 146 c, and the tissue interface pattern 152 may be a tissue interface pattern 152 c. The tissue contact surface 146 c may have a porosity of 35 pores per inch, which may define the tissue interface pattern 152 c having the shape and surface area of the struts 148 and the voids 150 shown in FIG. 3C. The struts 148 exposed at the tissue contact surface 146 c in the tissue interface pattern 152 c in FIG. 3C have a greater surface area than the struts 148 exposed at the tissue contact surface 146 b in the tissue interface pattern 152 b in FIG. 3B and the tissue contact surface 146 a in the tissue interface pattern 152 a in FIG. 3A. Accordingly, the contact force 115 required for the tissue interface pattern 152 c may be greater than the tissue interface pattern 152 b and the tissue interface pattern 152 a to produce a desired amount of tissue deformation.

The body mass 154 may be configured to create a desired amount of tissue deformation in combination with the tissue interface pattern 152. The body mass 154 may be selectable according to the tissue interface pattern 152. For example, the body mass 154 may be selected by material properties or sized sufficiently to create a desired amount of tissue deformation with the tissue interface pattern 152. Alternatively, the tissue interface pattern 152 may be selected appropriately according to the size or material properties of the body mass 154. In some embodiments, the body mass 154 may correspond to a weight that may provide the contact force 115 of the interactive body 114, which may be enhanced by other components of the system 110, such as the previously described absorbent member 138 or the sealing member 128. Herein, the body mass 154 and the weight of the body mass 154 may be defined or selected according to the thickness 144 of the interactive body 114. The thickness 144 of the interactive body 114 may also be the same as a thickness of the body mass 154. In some embodiments, the thickness 144 of the body mass 154 or the interactive body 114 may be between about 2 millimeters to about 8 millimeters. In some particular embodiments, the thickness 144 of the body mass 154 or the interactive body 114 may be about 5 millimeters.

Continuing with the discussion of FIGS. 3A-3C, a surface area of the struts 148 in the tissue interface patterns 152 a-c were described for a range of porosities at the tissue contact surfaces 146 a-c, respectively. A greater contact force 115 is required from the interactive body 114 to produce a set amount of tissue deformation for embodiments of the tissue interface pattern 152 having a greater surface area of the struts 148 or a higher porosity at the tissue contact surface 146. For embodiments of the tissue interface pattern 152 having a greater surface area of the struts 148 or a higher porosity at the tissue contact surface 146, the thickness 144 or weight of the body mass 154 may be increased to increase the contact force 115 of the interactive body 114 sufficiently to create the tissue deformation.

A system, dressing, or method employing the interactive body 114 according to this disclosure may stimulate tissue growth, providing a wound bed ready for grafting or epithelialization without the application of an external force, such as a compressive force, that may be associated with the application of conventional negative pressure wound therapy (NPWT). Conventional dressings that do not use negative pressure, referred to as non-NPWT dressings, typically use non-adherent interface layers, silicones, and similar elements to make them non-adherent to the tissue, less susceptible to tissue in-growth, and less likely to cause tissue disruption. Accordingly, non-NPWT dressings are typically designed to reduce or eliminate mechanical interaction with tissue, limiting their ability to stimulate tissue growth.

NPWT dressings may be designed to mechanically interact with tissue as a result of compressive and other forces applied to the tissue through the dressing by negative pressure generated by a negative pressure source. Being designed for use with negative pressure, these NPWT dressings do not typically produce sufficient mechanical interaction with tissue to stimulate or accelerate tissue growth without the application of negative pressure. As described herein, the interactive body 114 according to this disclosure may have a porosity at the tissue contact surface 146 less than about 39 pores per inch. In contrast, typical NPWT dressings have a porosity greater than about 40 pores per inch, which minimizes tissue in-growth into the NPWT dressings that can occur as a result of the application of negative pressure.

Referring to testing results shown in FIGS. 4A-4D, various test articles for the interactive body 114 were tested against two control articles. The test articles had varying void or pore sizes, material compositions, and structural features. The pore or void sizes varied from about 20 pores per inch to about 80 pores per inch. The materials tested included foams, such as ester-based and ether-based polyurethane foams; polyvinylalcohol foams; silicone; collagen compositions; and collagen coatings. The structures tested included varying mass or thickness; protrusions, such as silicone protrusions; bed-of-nails features; the addition of absorbent layers and compounds; and the addition of sealing layers or members, such as a medical drape. The testing sought a material, structure, and pore size for use as a dressing or with a dressing that would optimize the formation of granulation tissue at a tissue site, the quality of the granulation tissue, and the speed in which the granulation tissue is formed without the application of negative pressure.

FIG. 4A is a plot of Mean Percent Change in Wound Volume from days 0-6 for Test Articles 1-8 and Control Articles 1-2. FIG. 4B is a bar graph of Mean Granulation Tissue Thickness, measured in microns, for Test Articles 1-8 and Control Articles 1-2 produced over a 6 day testing period. FIG. 4C is a bar graph of Overall Inflammation, scored from 1-5, for Test Articles 1-8 and Control Articles 1-2 produced over a 6 day testing period.

FIG. 4D is a bar graph of Edema, scored from 1-5, for Test Articles 1-8 and Control Articles 1-2 produced over a 6 day testing period. Overall Inflamation and Edema were scored from 1-5 as follows: Score 0 indicating no edema; Score 1 indicating minimal edema; Score 2 indicating mild edema; Score 3 indicating moderate edema; Score 4 indicating marked or significant edema; and Score 5 indicating severe edema. Particularly for Test Articles 3, 4, 6, and 7, the test results show that the interactive body 114 according to this disclosure produced stimulated granulation response in the wound bed and edges of a test specimen; reduction in edema; and reduction in inflammation. Accordingly, the interactive body 114 provides a solution for stimulating the formation of quality granulation tissue, without the application of negative pressure, compared to conventional non-NPWT dressings.

In some illustrative, non-limiting examples a method for stimulating tissue growth at a tissue site may include providing the interactive body 114 including the tissue contact surface 146. The tissue contact surface 146 may include the plurality of struts 148 and the plurality of voids 150 exposed at the tissue contact surface 146. Further, the method may include positioning the tissue contact surface 146 in contact with the tissue site 112, and engaging the plurality of struts 148 and the plurality of voids 150 with a tissue at the tissue site 112 to create the contact force 115 on the tissue. Further, the method may include deforming the tissue at the tissue site 112 by operation of the contact force 115 without an application of reduced pressure.

In some embodiments, the method may include positioning the absorbent member 138 proximate to the interactive body 114 such that the interactive body 114 is positioned between the absorbent member 138 and the tissue site 112. Further, the method may include exerting the auxiliary force 139 on the tissue from the absorbent member 138 through the interactive body 114. Exerting the auxiliary force 139 on the tissue may include swelling the absorbent member 138 by absorbing fluid communicated from the tissue site 112 to the absorbent member 138 through the interactive body 114.

In some embodiments, the method may include covering the absorbent member 138 and the interactive body 114 at the tissue site 112 with a sealing member 128. The sealing member 128 may be configured to provide a seated space 130 between the sealing member 128 and the tissue site 112.

In some embodiments, the interactive body 114 may include the body mass 154, and the plurality of struts 148 and the plurality of voids 150 may define the tissue interface pattern 152 as described herein. In such embodiments, the method may include selecting the body mass 154 to produce the contact force 115 for deforming the tissue in combination with the tissue interface pattern 152. Selecting the body mass 154 may include sizing the body mass 154 to have a weight sufficient to produce the contact force 115 for deforming the tissue in combination with the tissue interface pattern 152.

In some embodiments, the method may include configuring the tissue interface pattern 152 to produce the contact force 115 for deforming the tissue in combination with the body mass 154. Configuring the tissue interface pattern 152 may include sizing the plurality of voids 150 and the plurality of struts 148 to produce the contact force 115 for deforming the tissue in combination with the body mass 154.

In some embodiments, the method may include determining a size of the body mass 154 to produce the contact force 115 as a function of a shape, geometry, or surface area of the tissue interface pattern 152. In some embodiments, the method may include determining a geometry or a surface area of the tissue interface pattern 152 to produce the contact force 115 as a function of a size of the body mass 154.

In some embodiments, the interactive body 114 may include or be formed of a porous foam carrying the plurality of struts 148 and the plurality of voids 150 at the tissue contacting surface 146 as described herein. In some embodiments, the method may include selecting the porous foam to have a porosity configured to create the contact force 115 for deforming the tissue. In some embodiments, the method may include selecting the porous foam to have a porosity according to a granulation tissue formation rate desired at the tissue site 112. A decrease in the porosity may produce a larger pore size, which may correspond to an increase in the granulation tissue formation rate as described herein.

The porosity of the porous foam may be less than about 39 pores per inch. For example, in some embodiments, the porosity of the porous foam may be between about 20 pores per inch to about 35 pores per inch.

While many of the apparatus, systems, and methods described herein have been illustrated for use with tissue sites or wounds that are at or near the epidermis of a patient, the apparatus, systems, and methods may similarly be used to treat subcutaneous tissue sites, tunnel wounds, or other undermined areas of tissue.

Although the subject matter of this disclosure has been provided by way of example in the context of certain illustrative, non-limiting embodiments, various changes, substitutions, permutations, and alterations can be made without departing from the scope of this disclosure as defined by the appended claims. Any feature described in connection to any one embodiment may also be applicable to any other embodiment. As such, the benefits and advantages described above may relate to one embodiment or may relate to several embodiments. Further, the steps of the methods described herein may be carried out in any suitable order, or simultaneously where appropriate. 

What is claimed is:
 1. A system for stimulating tissue growth at a tissue site, comprising: an interactive body configured to create tissue deformation at the tissue site, the interactive body comprising: a tissue contact surface configured to contact the tissue site, a plurality of struts exposed at the tissue contact surface, a plurality of voids exposed at the tissue contact surface, a tissue interface pattern defined by the plurality of struts and the plurality of voids at the tissue contact surface that is configured to engage the tissue site, and a body mass configured to create the tissue deformation in combination with the tissue interface pattern.
 2. The system of claim 1, wherein the interactive body is configured to create the tissue deformation without the application of an external force.
 3. The system of claim 1, wherein the interactive body is configured to create the tissue deformation without the application of a reduced pressure.
 4. The system of claim 1, wherein the plurality of struts and the plurality of voids are configured to be positioned in direct physical contact with the tissue site.
 5. The system of claim 1, wherein the interactive body comprises a porous substrate material.
 6. The system of claim 1, wherein the interactive body comprises a foam.
 7. The system of claim 1, wherein the interactive body comprises a hydrophobic material.
 8. The system of claim 1, wherein the interactive body comprises a hydrophobic reticulated polyurethane foam.
 9. The system of claim 1, wherein the tissue contact surface of the interactive body comprises a foam, and wherein the foam carries the plurality of struts and the plurality of voids, and wherein the plurality of struts and the plurality of voids are defined by a porosity of the foam.
 10. The system of claim 9, wherein the foam comprises a porosity between about 20 pores per inch to about 35 pores per inch.
 11. The system of claim 1, further comprising a sealing member configured to provide a sealed space between the sealing member and the tissue site, the interactive body configured to be positioned in the sealed space.
 12. The system of claim 11, further comprising an absorbent member positioned proximate to the interactive body in the sealed space, the interactive body configured to be positioned between the absorbent member and the tissue site.
 13. The system of claim 12, wherein the absorbent member is configured to absorb fluid communicated from the tissue site through the interactive body, and wherein the absorbent member is configured to swell and to exert an auxiliary force on the tissue site through the interactive body when the fluid is absorbed.
 14. The system of claim 1, further comprising an absorbent member positioned proximate to the interactive body, the absorbent member configured to swell and to exert an auxiliary force on the tissue site when the absorbent member absorbs a fluid.
 15. The system of claim 14, wherein the absorbent member is configured to absorb the fluid from the tissue site through the interactive body.
 16. The system of claim 14, wherein the absorbent member is configured to exert the auxiliary force on the tissue site through the interactive body.
 17. The system of claim 1, wherein the interactive body is formed of a fluid permeable material.
 18. The system of claim 1, wherein the body mass is selectable according to the tissue interface pattern.
 19. The system of claim 1, wherein the tissue interface pattern is selectable according to the body mass.
 20. A system for stimulating tissue growth at a tissue site, comprising: a porous foam comprising a tissue contact surface and a plurality of struts positioned at the tissue contact surface, the plurality of struts configured to contact the tissue site and to create tissue deformation at the tissue site; wherein the porous foam comprises a porosity between about 20 pores per inch to about 35 pores per inch; and wherein the porous foam is configured to provide a contact force at least between the plurality of struts and the tissue site to create the tissue deformation without the application of a reduced pressure.
 21. The system of claim 20, wherein the plurality of struts are exposed at the tissue contact surface.
 22. The system of claim 20, further comprising a plurality of voids, and wherein the plurality of voids and the plurality of struts are exposed at the tissue contact surface and configured to engage the tissue site.
 23. The system of claim 20, wherein the porous foam comprises a hydrophobic reticulated polyurethane foam.
 24. The system of claim 20, further comprising an absorbent member proximate to the porous foam, wherein the porous foam is configured to be positioned between the absorbent member and the tissue site.
 25. The system of claim 24, wherein the absorbent member is configured to absorb a fluid communicated from the tissue site through the porous foam, and wherein the absorbent member is configured to swell and to exert an auxiliary force on the tissue site through the porous foam when the fluid is absorbed.
 26. The system of claim 25, further comprising a sealing member configured to provide a sealed space between the sealing member and the tissue site, the porous foam and the absorbent member configured to be positioned in the sealed space.
 27. A method for stimulating tissue growth at a tissue site, comprising: providing an interactive body comprising a tissue contact surface, the tissue contact surface comprising a plurality of struts and a plurality of voids exposed at the tissue contact surface; positioning the tissue contact surface in contact with the tissue site; engaging the plurality of struts and the plurality of voids with a tissue at the tissue site to create a contact force on the tissue; and deforming the tissue at the tissue site by operation of the contact force without an application of reduced pressure.
 28. The method of claim 27, further comprising positioning an absorbent member proximate to the interactive body, wherein the interactive body is positioned between the absorbent member and the tissue site.
 29. The method of claim 28, further comprising exerting an auxiliary force on the tissue from the absorbent member through the interactive body.
 30. The method of claim 29, wherein exerting the auxiliary force on the tissue comprises swelling the absorbent member by absorbing fluid communicated from the tissue site to the absorbent member through the interactive body.
 31. The method of claim 30, further comprising covering the absorbent member and the interactive body at the tissue site with a sealing member configured to provide a sealed space between the sealing member and the tissue site.
 32. The method of claim 27, wherein the interactive body further comprises a body mass, and wherein the plurality of struts and the plurality of voids define a tissue interface pattern, and wherein the method further comprises selecting the body mass to produce the contact force for deforming the tissue in combination with the tissue interface pattern.
 33. The method of claim 32, wherein selecting the body mass comprises sizing the body mass to have a weight sufficient to produce the contact force for deforming the tissue in combination with the tissue interface pattern.
 34. The method of claim 27, wherein the interactive body further comprises a body mass, and wherein the plurality of struts and the plurality of voids define a tissue interface pattern, and wherein the method further comprises configuring the interface pattern to produce the contact force for deforming the tissue in combination with the body mass.
 35. The method of claim 34, wherein configuring the interface pattern comprises sizing the plurality of voids and the plurality of struts to produce the contact force for deforming the tissue in combination with the body mass.
 36. The method of claim 27, wherein the interactive body further comprises a body mass, and wherein the plurality of struts and the plurality of voids define a tissue interface pattern, and wherein the method further comprises determining a size of the body mass to produce the contact force as a function of a geometry or a surface area of the interface pattern.
 37. The method of claim 27, wherein the interactive body further comprises a body mass, and wherein the plurality of struts and the plurality of voids define a tissue interface pattern, and wherein the method further comprises determining a geometry or a surface area of the interface pattern to produce the contact force as a function of a size of the body mass.
 38. The method of claim 27, wherein the interactive body comprises a porous foam carrying the plurality of struts and the plurality of voids at the tissue contacting surface, and wherein the method further comprises selecting the porous foam to have a porosity configured to create the contact force for deforming the tissue.
 39. The method of claim 38, wherein the porosity of the porous foam is between about 20 pores per inch to about 35 pores per inch.
 40. The method of claim 38, wherein the porosity of the porous foam is less than about 39 pores per inch.
 41. The method of claim 38, further comprising selecting the porous foam to have a porosity according to a granulation tissue formation rate desired at the tissue site, wherein a lower porosity having a larger pore size corresponds to an increase in the granulation tissue formation rate.
 42. The method of claim 27, wherein the interactive body is configured to stimulate granulation response and to reduce edema and inflammation at the tissue site. 